This type of psoriasis usually appears as a large red area covered with yellow-green pustules. They tend to be one to two millimeters in diameter and are quite tender. The yellow color is caused by masses of white blood cells (polymorph leucocytes), which flood into any part of the skin that is damaged or infected, in order to fight infection and aid recovery.After seven to 10 days, the pustules become dispersed and a brown scale appears. This scale will start to shed as new pustules develop in other areas, often in a continuous cycle.The most common type of pustular psoriasis affects the palms and soles. It isn't normally itchy however it can be sore or uncomfortable to use either your hands or feet, for example if you are writing or walking.
Learn more about this type of psoriasis at:
http://www.internationaleczema-psoriasisfoundation.org/pustular_psoriasis.php4